Semiconductor memory devices capable of being used in, for example, portable electronic devices capable of processing large amounts of information are becoming more popular. These devices are typically required to have superior characteristics such as high speed, mass storage capacity, low power consumption, and the like.
These semiconductor memory devices typically have low power consumption as well as characteristics, such as the non-volatility of flash memory devices, the high operation speed of static random-access memory (SRAM) devices, the integration degree of dynamic random-access memory (DRAM) devices, and the like. These semiconductor memory devices may include, for example, ferroelectric random-access memory (FRAM) devices, magnetic random-access memory (MRAM) devices, phase-changeable random-access memory (PRAM) devices, and the like. FRAM devices, MRAM devices and PRAM devices typically operate with relatively low voltages.
Furthermore, these semiconductor memory devices may have superior data reading/writing characteristics compared to other memory devices, such as read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), DRAM, SRAM devices, and the like.
MRAM devices use magnetic characteristics. FRAM devices include non-volatile memory cells formed using ferromagnetic regions. The MRAM devices, the FRAM devices, and the like, are provided as magnetoresistance memory devices having anisotropic magnetoresistance, or giant magnetoresistance of ferromagnetic material. Thus, the memory cells may have characteristics, such as high resistance, low density, and the like.
Furthermore, the PRAM devices store data using structural phase-changes generated at a thin layer formed from an alloy including, for example, selenium (Se), tellurium (Te), and the like. The crystalline state and the amorphous state of the alloy are stably maintained in order to form a bi-stable switch. The PRAM devices may be used as a non-volatile memory cell. However, the operation speed of the PRAM device is typically slow. Furthermore, processes for manufacturing the PRAM devices are complex. The PRAM devices are typically not reliable.
Wires of nanometer scale are used in the semiconductor field. A memory device used as a non-volatile memory cell through electromechanical movement of wires has been proposed (hereinafter “electromechanical non-volatile memory device”). In the electromechanical non-volatile memory device, the wires move to make contact with an upper electrode pattern or a lower electrode pattern in response to a potential difference. The wires have a structure capable of maintaining the above contact state even when electric force has been removed.
The electromechanical non-volatile memory device may perform programming and erasing operations at a relatively high speed by using a low voltage. Furthermore, the cell structure of the electromechanical non-volatile memory device may be relatively simple so that it can be highly integrated.
An electromechanical non-volatile memory device is discussed in, for example, U.S. Pat. No. 6,924,538. As discussed therein, an upper portion and a lower portion of a wire are fixed by an insulating pattern. The wire may be damaged when the data is repetitively read, and thus defects may occur in the device. Furthermore, processes for manufacturing the electromechanical non-volatile memory device may be relatively complicated. It may also be difficult to form an electrode pattern between wires such that the electrode pattern does not make contact with the wires.